<template>
  <div class="home-page">

    <div class="banner">
      <div class="container">
        <h1 class="logo-font">conduit</h1>
        <p>A place to share your knowledge.</p>
      </div>
    </div>

    <div class="container page">
      <div class="row">

        <div class="col-md-9">
          <div class="feed-toggle">
            <ul class="nav nav-pills outline-active">
              <li v-if="user" class="nav-item">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'your_feed'
                  }"
                  exact
                  :to="{
                    name: 'home',
                    query: {
                      tab: 'your_feed'
                    }
                  }"
                >Your Feed</nuxt-link>
              </li>
              <li class="nav-item">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'global_feed'
                  }"
                  exact
                  :to="{
                    name: 'home'
                  }"
                >Global Feed</nuxt-link>
              </li>
              <li v-if="tag" class="nav-item">
                <nuxt-link
                  class="nav-link"
                  :class="{
                    active: tab === 'tag'
                  }"
                  exact
                  :to="{
                    name: 'home',
                    query: {
                      tab: 'tag',
                      tag: tag
                    }
                  }"
                ># {{ tag }}</nuxt-link>
              </li>
            </ul>
          </div>

          <div
            class="article-preview"
            v-for="article in articles"
            :key="article.slug"
          >
            <div class="article-meta">
              <nuxt-link :to="{
                name: 'profile',
                params: {
                  username: article.author.username
                }
              }">
                <img :src="article.author.image" />
              </nuxt-link>
              <div class="info">
                <nuxt-link class="author" :to="{
                  name: 'profile',
                  params: {
                    username: article.author.username
                  }
                }">
                  {{ article.author.username }}
                </nuxt-link>
                <span class="date">{{ article.createdAt | date('MMM DD, YYYY') }}</span>
              </div>
              <button
                class="btn btn-outline-primary btn-sm pull-xs-right"
                :class="{
                  active: article.favorited
                }"
                @click="onFavorite(article)"
                :disabled="article.favoriteDisabled"
              >
                <i class="ion-heart"></i> {{ article.favoritesCount }}
              </button>
            </div>
            <nuxt-link
              class="preview-link"
              :to="{
                name: 'article',
                params: {
                  slug: article.slug
                }
              }"
            >
              <h1>{{ article.title }}</h1>
              <p>{{ article.description }}</p>
              <span>Read more...</span>
              <ul class="tag-list">
                  <li class="tag-default tag-pill tag-outline" v-for="(item, index) in article.tagList" :key="index">{{item}}</li>
              </ul>
            </nuxt-link>
          </div>

          <!-- 分页列表 -->
          <el-pagination
            background
            @size-change="handleSizeChange"
            @current-change="handleCurrentChange"
            :current-page="page"
            :page-sizes="[10, 20, 30, 40]"
            :page-size="limit"
            layout="sizes, prev, pager, next"
            :total="articlesCount">
          </el-pagination>
          <!-- /分页列表 -->

        </div>

        <div class="col-md-3">
          <div class="sidebar">
            <p>Popular Tags</p>

            <div class="tag-list">
              <nuxt-link
                :to="{
                  name: 'home',
                  query: {
                    tab: 'tag',
                    tag: item
                  }
                }"
                class="tag-pill tag-default"
                v-for="item in tags"
                :key="item"
              >{{ item }}</nuxt-link>
            </div>
          </div>
        </div>

      </div>
    </div>

  </div>
</template>

<script>
  import {
    getArticles,
    getYourFeedArticles,
    addFavorite,
    deleteFavorite
  } from '@/api/article'
  import { getTags } from '@/api/tag'
  import { mapState } from 'vuex'

  export default {
    name: 'Home',
    async asyncData ({ query }) {
      const page = Number.parseInt(query.page|| 1)
      const limit = Number.parseInt(query.limit|| 20)
      const tab = query.tab || 'global_feed'
      const tag = query.tag

      const loadArticles = tab === 'global_feed'
        ? getArticles
        : getYourFeedArticles

      const [ articleRes, tagRes ] = await Promise.all([
        loadArticles({
          limit,
          offset: (page - 1) * limit,
          tag
        }),
        getTags()
      ])

      const { articles, articlesCount } = articleRes.data
      const { tags } = tagRes.data

      articles.forEach(article => article.favoriteDisabled = false)

      return {
        articles, // 文章列表
        articlesCount, // 文章总数
        tags, // 标签列表
        limit, // 每页大小
        page, // 页码
        tab, // 选项卡
        tag // 数据标签
      }
    },
    watchQuery: ['page', 'tag', 'tab'],
    computed: {
      ...mapState(['user'])
    },

    methods: {
      async onFavorite (article) {
        article.favoriteDisabled = true
        if (article.favorited) {
          // 取消点赞
          await deleteFavorite(article.slug)
          article.favorited = false
          article.favoritesCount += -1
        } else {
          // 添加点赞
          await addFavorite(article.slug)
          article.favorited = true
          article.favoritesCount += 1
        }
        article.favoriteDisabled = false
      },
      handleSizeChange(val) {
        this.$router.push({
                    name: 'home',
                    query: {
                      page: 1,
                      limit: val,
                      tag: this.$route.query.tag,
                      tab: this.tab
                    }
                  })
      },
      handleCurrentChange(val) {
        this.$router.push({
                    name: 'home',
                    query: {
                      page: val,
                      limit: this.limit,
                      tag: this.$route.query.tag,
                      tab: this.tab
                    }
                  })
      }
    }
  }
</script>
